Standardized lens photography with centralized grading of photographs has been used in clinical trials and epidemiologic studies of cataract. While photographic grading systems have been shown to be reliable, they are too expensive and complex to use in many studies. For some large studies, especially those with many centers or those in which lens changes are of secondary concern, it would be useful to have a simple clinical lens grading system that is reliable and that can be used with minimal training of examiners. Several clinical lens grading systems have been developed and found to be reliable in the hands of dedicated lens researchers, but the systems have been difficult for other ophthalmologists to use reliably. The Age-Related Eye Disease Study (AREDS) has developed a simplified clinical cataract grading system to assess the severity of nuclear, cortical and posterior subcapsular cataracts, the 3 main types of age-related cataract. The system is designed to require minimal examiner training for persons already proficient in the use of the slit lamp. A total of 150 participants with cataracts of varying severity, who are already participating in other NEI protocols, will be recruited to evaluate the reliability of the system. After being dilated, each participant will have a lens grading performed independently by 2 examiners. To provide information on the validity of the clinical gradings, lens photographs will be taken and graded using the detailed AREDS system for grading photographs. The data will allow us to evaluate (1) the agreement between the AREDS clinical lens grading system and the AREDS photographic system of grading lens opacities, and (2) the agreement on assessment of cataract severity among ophthalmologists (with varying subspecialty) using the AREDS clinical lens grading method.